King of Prussia (1797–1840), son
and successor of Friedrich Wilhelm II. Also known as Frederick William.
Well-intentioned but weak and vacillating, he endeavored to maintain
neutrality in the Napoleonic Wars. In 1806, French troops were massed on
Prussia’s frontier and he was forced to take up arms against France.
His crushing defeat by the French at Jena and the humiliating Treaty
of Tilsit (1807), which virtually made Prussia a French vassal,
served to waken the king to the need of reconstruction in Prussia.
Unable to carry through the reforms himself, he was far-sighted enough
to appoint capable ministers.

The reforms of Karl vom und zum Stein, Karl August von Hardenburg,
and Scharnhorst laid the basis of the modern Prussian state and prepared
for the eventual war against Napoleon. Forced to send an auxiliary force
to aid Napoleon’s Russian campaign, the king was finally persuaded to
support the Convention of Tauroggen, concluded with the Russians
by the commander of the Prussian auxiliary force, General Yorck von
Wartenburg. A few weeks later a military alliance with Russia was
signed, and in March 1813, the king declared war on France. After
Napoleon’s defeat and the Congress of Vienna, which he
attended, Friedrich Wilhelm III grew more reactionary. Influenced by
Czar Alexander I and by Metternich, he joined the Holy Alliance
and refused to grant the constitution he had promised. His rule was
largely influence by his wife, Queen Louise von Mecklenburg-Strelitz,
who far more popular than he, but she died in 1810. His elder son
Friedrich Wilhelm IV succeeded him, and his second son was to become
Emperor Wilhelm I. He died in June 1840 in Berlin..